18 MILLIPEDES 



sternites are free. In this feature they contrast with all other 

 Chilognatha except the Oniscomorpha. The tergites are provided 

 with three pairs of symmetrically placed bristles and are usually 

 keel-shaped or carinate at the sides, but have no stink glands. 

 There is a pair of spinning papillae on the last tergal plate. The 

 order is represented by several families, of which the Chor- 

 deumidae, Brachychaeteumidae and Craspedosomidae are found 

 typically in Europe and North America in the northern hemisphere, 

 while the Heterochordeumidae range from tropical Asia to New 

 Zealand in the southern hemisphere. The British forms are small, 

 pale animals and include species of Brachychaeteumay Micro- 

 chordeuma, Craspedosoma rawlinsi which is more richly coloured 

 and has lateral tergal expansions like those of the Polydesmidae, 

 and Polymicrodon polydesmoides, which usually inhabits the leafy 

 floor of deciduous woodlands. 



The flat-backed millipedes of the order Proterospermophora 

 have 19 or 20 tergal plates welded with the pleura and sternites to 

 form solid rings usually provided with lateral shelf-like carinae. 

 In this, they diflPer from other flat-backed forms (Brachychae- 

 tumidae). There are no eyes, no spinning papillae on the last tergal 

 plate, and the pores of the repugnatorial glands when these are 

 present are borne on the lateral carinae. The members of this order 

 belong to several families such as the Polydesmidae, Crypto- 

 desmidae and Strongylosomidae, and are referred to a vast number 

 of genera and species found in all the countries of the world. Some 

 of the tropical species are large reaching a length of about six 

 inches, and may be brightly coloured. The British fauna includes 

 a number of species of Polydesmidae of which Polydesmiis angustus 

 is the most common, a doubtful record of Eumastigonodesmus 

 bond (family Mastigonodesmidae) and some representatives of the 

 family Strongylosomidae. These include Macrosternodesmus pali- 

 cola, the smallest British Diplopod, Ophiodesmiis albonanus and 

 Oxidus (Paradesmiis) gracilis which is found in greenhouses all over 

 the country. 



The Lysiopetalidae, which are usually regarded as a separate 

 sub-order from the previous families which are grouped together 

 in the sub-order Polydesmoidea, are not represented in the 

 British faunal list. These animals are found in Europe, Asia Minor 



